Process for producing textured thermoplastic yarns

ABSTRACT

An improved process for the production of springy, textured thermoplastic yarns wherein the yarns are compacted and compressed in an enclosed space by means of a flow of compressed fluid heated at a temperature that allows for the fixing of the yarn, a portion of the fluid affecting the movement of the yarn and another portion escaping to the side from the enclosed space, such process being characterized in that the escape of fluid is effected at a pressure which is lower than the feed pressure, but higher than atmospheric pressure. The apparatus for effecting such process comprises a suction nozzle constituting a passage for the yarn and a delivery tube for admission of pressurized fluid, a tubular chamber communicating with the nozzle, and having orifices therein, a housing defining a closed space enclosing at least a portion of the length of the tubular chamber and having a pressure regulation system associated therewith, and means for controlling the discharge of the treated yarn.

United States Patent Blanc et a]. i i

[451 Nov. 28, 1972 [s41 PROCESS FOR PRODUCING TEXTURED THERMOPLASTIC YARNS [72] Inventors: Charles Blanc, St-Romain au Mont D0r; Jean Joly, Brindas, both of [2]] Appl. No.: 56,880

[30] Foreign Application Priority Data PrimaryExaminen-Robert R. Mackey Attorney-Sherman and Shalloway ABSTRACT An improved process for the production of springy, textured thermoplastic yarns wherein the yarns are compacted and compressed in an enclosed space by means of a flow of compressed fluid heated at a temperature that allows for the fixing of the yarn, a portion of the fluid affecting the movement of the yarn and another portion escaping to the side from the enclosed space, such process being characterized in that the escape of fluid is effected at a pressure which is July 24, 1969 France lower h the f d pressure, but higher than U S C 28/72 14 mospheric pressure. 51 Im. c1. 602 n12 Thqapvaraws for effecting Such process Comprises a 58 Field of Search ..28/72.l1, 72.12, 72.14 SW10" nozzle consuwilng a Passage q the X and n a delivery tube for adnussion of pressurized fiLlld, a tu- 56 R f bular chamber communicating with the nozzle, and l erences Cl having orifices therein, a housing defining a closed UNITED STATES PATENTS space enclosing at least a portion. of the length of the 1 tubular chamber and having a pressure regulation 3343240 9/1967 7 I 4 X system associated therewith, and means for control- 3 576 058 4/1971 b 28/72 H x ling the discharge of the treated yarn.

4 Claim, 2 Drawing Figures PATENTEDunvza I972 3. 703' 754 %O 1 IO FIG. 2

INVENTORS CHARLES BLANC JEAN JOLY ATTORNEYS PROCESS FOR PRODUCING TEXTURED THERMOPLASTIC YARNS particularly the present invention is directed to an improved process and apparatus wherein a compacted and compressed yarn is produced under the influence of a compressed heated fluid wherein a portion of the fluid affects the movement of the yarn and a further portion escapes from the side of the apparatus.

Many processes have been developed for modifying the appearance and feel of synthetic yams. Thus, it is well known to produce such yarns in the form of continuous filaments. Such continuous filaments have the disadvantage in that for a number of applications, for example in clothing, they lack bulk and have insufficient covering capacity. Their conversion into cut fiber, which is spun by the usual methods of the textile industry, only partially resolves the problem and often gives rise to a further disadvantage, i.e. pilling." It is for this reason that processes for crimping or texturing continuous filaments have been. so extensively developed.

The oldest such method consists in subjecting the filaments to an overtwist, which is set, generally by a thermal treatment, and then to an untwisting, these successive operations being carried out continuously if the false-twist process is employed.

In another method, a heated yarn is passed over a knife-edge along an acute-angled path, of which the apex is situated at the knife-edge. It is also known to produce bulky yarns having loops, by passing a multifilament yarn through a current of compressed fluid actuated with a whirling movement.

Also, another known method of crimping continuous yarns, known as stuffer crimping, consists in stuffing the yarns under pressure in a confining crimping chamber provided at its outlet with a tiltable or hinged flap or other counterpressure device, the deformations obtained being set by thermal treatment, usually within the crimping chamber.

The stuffer crimping process has the advantage that it gives a high-bulk yarn having no loops (which often give the made-up articles a rough feel) and of which the elasticity, which is appreciably lower than that of yarns treated by the first two processes referred to above, is very suitable for the production of many articles of clothing, notably sweaters. However, industrial application of such procedure has the disadvantage that the procedure produces a yarn whose filaments have an inphase crimp and which, in addition, possess irregularities in dyeing affinity.

For the practical application of this process, the yarn is introduced with the aid of a pair of rollers into a crimping chamber in which it becomes accumulated until its pressure is sufficient to overcome the pressure of the counter-pressure device preventing it from leaving the chamber. The apparatus employed comprises a number of moving mechanical parts, which is always a disadvantage when it is desired to operate at high speed.

. An improvement over such conventional processes for the production of a crimped yarn has been illustrated, for example, in French Patent 1,289,491, as well as U.S. Pat. Nos. 3,373,470 and 3,482,294.The

basic process such as set forth in such French and U.S. patents consists of crimping the yarn by cramming or stuffing whereby the yarn is passed into a confined space by means of a flow of compressed fluid, the fluid being heated at a temperature which permits the setting of the yarn, a portion of the fluid assuring the progression of the yarn and a further portion escaping laterally from the restricted space within which the crimping takes place. Such a basic process as set forth in the above noted patents difiers from the conventional procedures described above in that the cramming or stufiing of the crimping operation is not effected by stopping the yarn or bunching the same against a mechanical obstacle but rather, it is due to the expansion of the fluid at the level of the fluid exhaust holes. Accordingly, in such process the fluid provides the function of supplying the yarn, advancing the yarn, and further acts as an agent for the formation of bunching.

While such a process such as set forth in the aforenoted patents has solved many of the deficiencies process is not in itself without certain disadvantages.

1 Accordingly, although such a process has proved to be satisfactory for the industrial production of texturized yarns and although such process is adequate for high speed production there is a limit to the number of parameters that can be involved if it is necessary to obtain certain yarn properties, particularly with regard to the springiness of the yarn, or where it is desired to increase the rate of production still further it has been found necessary to extend the nozzle, which, of course, imposes a practical economic limitation on the above described procedure. For this reason, the use of a process such as previously described is limited and certain speeds of production cannot be exceeded.

Additionally, such a process as described above has the disadvantage that it produces a relatively soft bunching or piling which lacks the desired flexibility. Various attempts to eliminate such disadvantage as well as those set forth above have been made such as, for example, by exposing the yarn to two successive thermal treatments, e.g., by means of a fluid. Similarly, it has been attempted to eliminate the foregoing disadvantages by effecting a cooling treatment at the outlet of the texturizing nozzle such as by means of an air jet. Finally it has even been suggested that a waved yarn could be thermally treated by putting it into contact with a gas or a saturated or superheated vapor, possibly under pressure, so as to continuously vapor treat the yarn after curling. All such suggestions however, involve the same drawback that the thermal treatment of the yarn is not directly related to the deformation treatment in the texturizing process so that advantageous results with regard to flexibility, springiness, and speed of production cannot be improved.

To overcome some of the deficiencies enumerated above specifically with regard to the relatively soft bunching or piling and the lack of flexibility of the crimped yam, it has been suggested that the yarn which is crimped by the fluid treatment can have a core yarn associated therewith so as to permit a more consistent bunching and a better heat setting of the yarn. Such a process is the objectof U.S. Pat. No. 3,438,105. The use of such a core yarn as set forth in U.S. Pat. No. 3,438,105 has been found annoying in connection with the bunching operation for as the texturizing speed increases, the treatment becomes more and more difficult due to the presence of the core yarn. Accordingly, until the development of the present invention the industry has long sought a still further improved process which would eliminate the various deficiencies of the previously described procedures while introducing no further variables presenting additional difficulty. This has now been accomplished in accordance with the present invention whereby it has been discovered that a very springy, texturized thermoplastic yarn can be obtained by compacting and compressing yarn in an enclosed space by means of a flow of compressed fluid heated at a temperature that allows the fixing of the yarn wherein a portion of the fluid insures the movement of the yarn and a further portion escapes to the side from the enclosed space, such process being characterized in that the escape of fluid is effected at least in part at a pressure which is lower than the feed pressure, but higher than atmospheric pressure. Accordingly it has been discovered in accordance with the present invention that by making the fluid escape into a contained space kept at a pressure higher than atmospheric pressure, rather than by letting the fluid escape directly into the atmosphere it is possible to obtain an excellent setting of the yarn at high speed and to produce a yarn which is very springy and which has an improved elasticity and curl. Moreover, it has been discovered that in accordance with the present invention that the process as described above can provide for excellent fixing of the curl even at high speed so as to allow the texturizing to take place together with a shortening of the necessary thermal fixing.

Accordingly, it is a principal object of the present invention to provide a process for the crimping of thermoplastic yarns which process and apparatus eliminate the inherent deficiencies of previously utilized systems.

It is a further object of the present invention to provide such a process for the crimping of thermoplastic yarns wherein such crimping is effected by compacting and compressing the yarn in an enclosed space by means of a fluid with lateral escape of the fluid, the process being characterized in that the escape of fluid is effected at least in part at a pressure which is lower than the feed pressure but higher than atmospheric pressure.

Yet a further object of the present invention comprises an apparatus for effecting the production of very springy, texturized thermoplastic yarns by compacting and compressing the yarn in an enclosed space by means of a flow of compressed fluid such apparatus comprising a suction nozzle, a tubular chamber communicating with the nozzle, said chamber having orifices therein, a closed space enclosing at least a portion of the length of the tubular chamber, means to control the pressure regulation of the system and means to control the discharge of the treated material.

Still further objects and advantages of the novel process and apparatus of the present invention will become more apparent from the following more detailed description thereof.

All of the foregoing advantages and objects of the present invention are achieved through a process and apparatus whereby very springy, texturized thermoplastic yarn can be obtained by compacting and compressing yarn in an enclosed space by means of a flow of compressed fluid heated at a temperature that allows for the fixing of the yarn wherein a portion of the fluid assures the movement of the yarn and another portion escapes to the side of the enclosed space, the process being particularly characterized in that such escape of fluid is effected at least in part at a pressure which is lower than the feed pressure but higher than atmospheric pressure. In this regard, it was discovered in accordance with the present invention that by allowing the fluid to escape not directly into the atmosphere, but into a contained space kept at a pressure higher than atmospheric pressure, it is possible to obtain an excellent setting of the yarn at a high speed. In addition it has been unexpectedly discovered in accordance with the present invention that through such a procedure and through the use of the apparatus of the present invention it is possible to obtain an improvement in the elasticity, springiness, and curl of the thermoplastic yarn which is obtained. Such advantages of course are combined with a good fixing of the curl produced even at high speeds of texturizing together with the aforementioned shortening of the thermofixing means.

In accordance with the present invention the pressure of the escaping fluid is preferably less than half the feed pressure, although, again, it is necessary in accordance with the present invention that the pressure of the escaping fluid be greater than atmospheric pressure. In this respect, it is again pointed out that it is the characteristic feature of the present invention that the fluid does not escape directly into the atmosphere as with previous processes, but, rather, the fluid escapes into a contained space kept at a pressure higher than atmospheric pressure.

As in accordance with previous procedures for the crimping of thermoplastic yarns the fluid medium which is employed in accordance with the present invention is advantageously saturated steam. Additionally, however, as with previous processes the fluid which is used in the crimping process may comprise hot air under pressure or a suitable liquid under pressure in addition to the saturated steam under pressure. For the purposes of providing the necessary crimping and fixing of the crimped yarn, however, the use of saturated steam as set forth above is particularly advantageous.

The filaments which are crimped in accordance with the present invention include both single continuous filaments and groups of continuous filaments or short fibers, for example, tows, yarns, and groups of yarns composed of filaments having the same or different count, cross-section or composition. The filaments which are usable in accordance with the present invention may be those which have come directly from the spinning machine, or, may have undergone preliminary treatments of well known types which do not in any way interfere with the crimping process of the present invention.

As indicated previously, the process and apparatus of the present invention are specifically adapted for the crimping of thermoplastic filaments. In this regard, the present invention is applicable to any and all thermoplastic filaments having sufficient strength to withstand the action of the current of fluid in accordance with the present invention without breaking. Such filaments are, for example, the artificial and synthetic filaments based upon cellulose acetate and tri-acetate, polyamides; polyesters, polyolefins, polyacrylonitrile, polyvinyl derivatives, etc. It should be quite obvious that in accordance with the present invention the operating conditions such as temperature and the pressure of the heating fluid depend upon the nature of the filaments, their count, and also their speed of travel. In accordance with the present invention, however, thetemperature of the heating fluid must be such as to set the filaments under the operating conditions employed.

As indicated previously, the process of the present invention may be applied to various types of filaments including for example, those single continuous filaments and groups of continuous filaments or short fibers in the forms of tows, etc. Accordingly, by utilizing various types of filaments in accordance with the process of the present invention, various fancy yarns can be obtained. Such production of fancy yarns utilizing a fluid crimping means is discussed in more detail in US. Pat. No. 3,373,470, the disclosure of which is herein incorporated by reference.

Similarly it should be quite obvious that the process of the present invention can be combined with other treatments of the filamentary material including for example, a dyeing treatment, treatment with swelling agent, treatment with a reserve agent, etc. Here again, such additional treatments which can be combined with the process of the present invention are more fully set forth in French Patent 1,491,449 and U.S. Pat. No. 3,373,470.

As indicated previously, the process of the present invention is carried out in connection with apparatus which comprises: a suction nozzle providing a passage for the yarn and a delivery tube for admission of pressurized fluid; a tubular chamber communicating with such nozzle, said chamber providing orifices; a closed space enclosing at least a portion of the length of the tubular chamber, such closed space being associated with a pressure regulated system or means; and means for the control of the discharge of the treated material.

Such apparatus in accordance with the present in- I vention is further illustrated by reference to the drawings wherein:

FIG. 1 is a diagramatic cross-sectional view illustrating one embodiment of the present invention; and

FIG. 2 is a further diagramatic cross-sectional view illustrating another embodiment of the present invention.

In the figures, like numerals represent like elements throughout. In accordance with FIG. 1, a yarn l is introduced into the longitudinal passage 2 of a nozzle 3. The crimping fluid, i.e. saturated steam is introduced into nozzle 3 through passage 4 In accordance with the present invention it is preferred that the crimping fluid, i.e. steam introduced through passage 4 be at a pressure of from about 4 bars to bars. It should be obvious however that the specific pressure utilized depends upon many variables, including the degree of crimping desired, the nature of the thennoplastic yarn filaments, and the dimensions of the crimping zone. Similarly the temperature of the crimping fluid is generally within the range of 150C to 183C although slightly higher or crimping fluid through the space defined by tubular chamber 5. As seen in FIG. 1 tubular chamber 5 is furnished with orifices 6 through which the crimping fluid escapes into a confined space 7. As indicated previously, the pressure in confined space 7 is regulated to be higher than atmospheric pressure, the pressure being maintained in the confined space through a pressure regulating means 8 of any known conventional type. As indicated previously, the pressure within the confined space 7 is preferably less than one-half of the feed pressure, i.e., the pressure of the crimping fluid introduced through passage 4. Accordingly, the pressure within confined space 7 is generally within the range of from about 0.5 bars to about 4 bars.

In the embodiment illustrated in FIG. 1 the crimped or compacted thermoplastic material 9 exits from the tubular chamber 5 at a speed which is controlled by two rollers 10 and 11. Again it is pointed out that it is a characteristic feature of the process and apparatus of the present invention that at least a portion of the compacting or crimping fluid escapes into a confined space maintained at a pressure higher than atmospheric pressure and, the fluid does not escape directly into the atmosphere. As can be seen in FIG. 1', the major portion of the compacting fluid will escape through orifices 6 into the confined space 7 and will not exit or escape at the outlet end of tubular chamber 5.

A modification of the apparatus of FIG. 1 is illustrated in FIG. 2. Here again, in FIG. 2, a yarn l is introduced into the longitudinal passage 2 of a nozzle 3. The crimping fluid, i.e. saturated steam is introduced into nozzle 3 through a passage 4 in the same manner as described in connection with FIG. 1.

Again, the yarn 1 moves along under the action of the crimping fluid through the space defined by tubular chamber 5. Thus, as seen in FIG. 2, tubular chamber 5 is furnished with orifices 6 through which the crimping fluid escapes into a confined space 7. Again the pressure in confined space 7 is regulated to be higher than atmospheric pressure, the pressure being maintained in the confined space through a pressure regulating means 8 of any known conventional type.

As shown in FIG. 2, however, the means for controlling the egress of the crimped thermoplastic yarns constitute a tube 12 which extends the tubular chamber 5 beyond the confined space 7 into which the crimping fluid escapes. As seen in FIG. 2, such tube 12 further contains orifices 13 which again allow for the further escape of any additional crimping fluid directly into the atmosphere. It can be seen, however, by reference to FIG. 2 that in accordance with the embodiment shown in FIG. 1 the major proportion of the crimping fluid will escape from tubular chamber 5 through orifices 6 into confined space 7 maintained at a pressure higher than atmospheric pressure and preferably less than one-half of the pressure of the crimping fluid.

The process and apparatus of the present invention will now be described by reference to the following specific examples. It is to be understood, however, that such examples are presented for purposes of illustration only and the present invention is in no way to be deemed as limited thereto.

EXAMPLES 1 to 7 In these examples the apparatus of FIG. 1 was used, the apparatus having an overall length of about 50 cm. The texturizing fluid was saturated steam.

Yarns of different deniers made of polyhexamethylene adipamide (Nylon 66) were treated in accordance with the present'invention.

Operating conditions and yarn characteristics are in dicated in the following table 1, in which P, is the feed pressure of the fluid in nozzle 3 and P is the fluid pressure in the enclosure 7. The pressures are those which were taken by manometer.

Elasticity was measured by the following test:

A sample of 10 meters of yarn to be tested was treated for minutes at 130C in saturated steam in an enclosure. Then, a length of 50 cm of yarn taken from this sample was loaded by 0.045 g/dtex (0.05 g/den) calculated before texturizing. The length L, of the yarn was then measured.

The load was replaced by a lesser load of 0.0009 g/dtex (0.001 g/den) on the yarn before texturizing. This load was maintained for 1 hour and then the length L of the yarn was measured. The elasticity of the yarn is given by the following formula:

(L, L2)/L2 100 The value indicated corresponds to an average of six tests.

TABLE 1 Material Yarn Fluid Elastic- Curl Ex. Nylon 66 speed pressure ity in (V; wave in m/mn in kg/cm per cm) P, P l ll60 dtex/ 400 7 0.5 l2.3 6.1

60 strands 2 H60 dtex/ 400 7 i 13.3 6.l

60 strands 3 1160 dtex/ 400 7 L5 l6.2 8.3

60 strands 4 H6O dtex/ 400 7 2 15.9 8.2

60 strands ll60/60 H25 2.75 8.6 580/30 400 7 L3 29.7 10.] [10/34 400 7 0.6 15.3 l2.l

EXAMPLES 8 and 9 These examples are intended to show the significance of the thermal treatment according to the present invention by means of a test which consists in application of the method described by STA'ITON in the Journal of Polymer Science J B Vol. 2, pages l,l l 3 l,l l6 (l96 l) and by ZUBOV and TSVANKIN in Polymer Science USSR," Vol. 6, No. 12, pages 2,358-2,367 (1964), to determine the defracted curve of intensity along the meridian as a function of the angle of defraction.

Taking into account the curve of air diffusion, the effect of the quantity of microfissures and integrated value of defracted intensity is determined, which is a growing function of the temperature and duration of the thermal treatment undergone by the yarn. This is designated as the degree of influence of thermal treatment. This method allows comparison of the yarns wherein the only difference is in the intensity and the duration of the thermal treatment.

The values which are indicated, which depend upon experimental conditions, especially of the sample and of the apparatus, are indicated as in the articles cited above in arbitrary units.

In these examples a polyhexamehtylene adipamide (nylon 66) yarn, 1,160 dtex/ strands, drawn at a level of 4.53 in conditions summarized in the following table 2 in which, as in the preceding examples, P, represents pressure feed of the saturated steam and P the pressure of the saturated steam inside the enclosure 7.

By way of comparison, there are values indicated in this table which were obtained for identical samples treated at pressure P,, pressure P being Zero, but fixed in an autoclave during a period of 2 hours at 145 C. The indicated pressures are those read on the manometer.

These two examples are only distinguished from each other by the rate of texturizing.

Bulk was determined by Koninghs test.

it can be seen from the above that, on one hand, there was a significant improvement in the thermal treatment (higher value of degree of influence in the thermal treatment), in elasticity and curl, and on the other hand, with reference to a control, that with a great increase of pressure P, (control not fixed, treated at pressure P,, respectively equal to 3.5 and 8 kglcm there was a slight difference in the degree of influence of the thermal treatment, in contrast to what happens in accordance with the present invention.

EXAMPLE 10 In this example, the effect of pressure P is shown. For this purpose a polyhexamethylene adipamide yarn l,l60/dtex/60 strands, drawn to 4.4, was again treated in saturated steam.

Table 3 which follows gives the values of pressures P, and P and of the corresponding degree of influence of the thermal treatment for the same rate of texturizing, namely 1,000 m/mn. 1

TABLE 2 Fluid Degree of Curl pressure influence in kgJcmfi Yarn of the Elaswave rate thermal tlcity, Bulk. per Example Kind of yarn P, I; in m./mn treatment percent ccJg. cm

(outrul not list-(l. 8.2 8.3 1.8 5 d0. .v 9.4 14.7 2.20 7.2 (ontrnl lixvd for 2 hrs. at 145 (1 26.6 22.4 2.40 6.4

. 1 .2fi.l 29.5 12.8 7.7 Ym'n tn-att'tl :ii'mrillng lo lhv inventimn 16. 7 .28 2. 8 J. (i (ontiul not lixutl 7.4 8.1 1. 4. l .H) 11.7 22.1 (3.! 9. 21'.) 17. 1 2. '2 6.13 .212. 8 221.5! .2. 7 8 H. 7 17.0 12.125 ll TABLE 3 P P Degree of Influence of kg/cm kg/cm the Themtal Treatment Arbitrary Units It will be noted that by varying the values of pressure P there may unexpectedly be a considerable effect on the degree of influence of the thermal treatment. It should be noted however that the yarn in this example I was different in its degree of drawing and its conditions of spinning from the yarn of Examples 8 and 9 and therefore the values in the same arbitrary units for degree 'of influence of thermal treatment cannot be compared with thoseof Examples 8 and 9.

EXAMPLE 1 1 EXAMPLE 12 In this example the apparatus of FIG. 2 was used with .an overall length of 560 mm, the length of tube 12 being 120 mm.

A polyhexamethylene adipamide yarn (1,160

dtex/60 strands) was treated under the following conditions:

P 7.4 kg/cm P 1.0 kg/cm Speed of texturizing 400 m/mn The yarn which was obtained had an elasticity of 23 percent.

The above examples show that by varying a single parameter, pressure P of the fluid in: the enclosed space, the elasticity, the curl and the degree of influence of the thermal treatment can be varied. This unexpected result is very important industrially in that,

Moreover, this texturiaing process as shown by Example 12 allows work at texturizing rates that are quite unusual with normal texturizing pressures.

in addition the foregoing exemplifications clearly illustrate the advantages of the process and apparatus of the present invention over conventional systems for the crimping of thermoplastic yarns,v even those systems which have heretofore utilized a crimping fluid. In this respect, in addition to the foregoing advantages with regard to elasticity, curl, and the degree of influence of thermal treatment, it can be seen from the foregoing examples that the process and apparatus of the present invention allow one to operate at texturizing rates which could not be heretofore utilized with normal texturizing procedures. This, therefore, constitutes a clear advantage of the present invention over any and all systems heretofore developed.

While the present invention has been illustrated primarily with regard to the foregoing exemplification, it should be obvious that the present inventionis not in any way to be deemed as limited thereto, but must be construed as broadly as all or any equivalents thereof.

What is claimed is:

l. A process for the preparation of a thermoplastic texturized yarn comprising compacting and compressing a yarn in a tubular chamber by means of a flow of compressed fluid, said tubular chamber being defined by a continuous wall of uniform dimensions on the one hand, it makes use of the texturizing fluid it- 1 throughout the length thereof contacting the yarn and having openings along the length thereof, fixing the yarn in said tubular chamber by said fluid being heated to fixing temperature for the yarn, supplying said. fluid axially at one end of said tubular chamber to effect crimping of the yarn initially in said tubular chamber and subsequent movement of the yarn through said tubular chamber, at least a part of said fluid escaping laterally from said tubular chamber along the length thereof through said openings into an outer chamber surrounding said tubular chamber, said outer chamber receiving fluid only from said tubular chamber, and maintaining the pressure in said outer chamber at a pressure greater than atmospheric pressure but less than the feed pressure of said compressed fluid.

2. The process of claim 1 wherein said enclosed space into which the compressed fluid escapes is maintained at a pressure which is less than one-half that of the feed pressure of said compressed fluid.

3. The process of claim 2 wherein said compressed fluid is saturated steam.

4. The process of claim 1 wherein said compressed fluid is saturated steam. 

1. A process for the preparation of a thermoplastic texturized yarn comprising compacting and compressing a yarn in a tubular chamber by means of a flow of compressed fluid, said tubular chamber being defined by a continuous wall of uniform dimensions throughout the length thereof contacting the yarn and having openings along the length thereof, fixing the yarn in said tubular chamber by said fluid being heated to fixing temperature for the yarn, supplying said fluid axially at one end of said tubular chamber to effect crimping of the yarn initially in said tubular chamber and subsequent movement of the yarn through said tubular chamber, at least a part of said fluid escaping laterally from said tubular chamber along the length thereof through said openings into an outer chamber surrounding said tubular chamber, said outer chamber receiving fluid only from said tubular chamber, and maintaining the pressure in said outer chamber at a pressure greater than atmospheric pressure but less than the feed pressure of said compressed fluid.
 2. The process of claim 1 wherein said enclosed space into which the compressed fluid escapes is maintained at a pressure which is less than one-half that oF the feed pressure of said compressed fluid.
 3. The process of claim 2 wherein said compressed fluid is saturated steam.
 4. The process of claim 1 wherein said compressed fluid is saturated steam. 